Function createSignatureBase

http/unstable_message_signatures.ts:705–747

(
  options: CreateSignatureBaseOptions,
)

 * @returns The signature base string.
 */
export function createSignatureBase(
  options: CreateSignatureBaseOptions,
): string {
  const { message, params, request: relatedRequest } = options;
  const components = params.components.map(normalizeIdentifier);

  const seen = new Set<string>();
  const lines: string[] = [];
  const parsedUrl: { value?: URL } = {};
  const relatedParsedUrl: { value?: URL } = {};
  for (const id of components) {
    if (id.name === "@signature-params") {
      throw new TypeError(
        `"@signature-params" must not be listed in covered components`,
      );
    }
    if (id.name !== id.name.toLowerCase()) {
      throw new TypeError(
        `Component name "${id.name}" must be lowercase`,
      );
    }
    const serializedId = serializeComponentIdentifier(id);
    if (seen.has(serializedId)) {
      throw new TypeError(
        `Duplicate component identifier ${serializedId} in covered components`,
      );
    }
    seen.add(serializedId);
    const value = resolveComponentValue(
      id,
      message,
      parsedUrl,
      relatedRequest,
      relatedParsedUrl,
    );
    lines.push(`${serializedId}: ${value}`);
  }

  const sigParamsValue = buildSignatureParamsValue(components, params);
  lines.push(`"@signature-params": ${sigParamsValue}`);

  return lines.join("\n");
}

// =============================================================================
// Input Validation